The LIBS instrument is a laboratory system using laser excitation at 266 nm (4th harmonic of a Q-switched Nd: YAG laser (Lotis TII, LS-2147), 15 ns pulses, 1 Hz repetition rate). LIBS spectra are recorded using a 0.2 m Czerny-Turner spectrograph (Andor, Shamrock Kymera-193i-A) equipped with a grating of 1800 grooves/mm (blazed at 265 nm) and coupled to a time-gated intensified charge-coupled device (ICCD) camera (Andor Technology, iStar CCD 334, 1024x1024 active pixels, 13 μm x 13 μm pixel size). The ICCD detector is synchronized with the Q-Switch output electrical signal that triggers the laser pulse. The laser beam is directed to the samples' surface by using mirrors at an incidence angle of 45°. Focusing with a 10 cm focal length lens allows fluences in the 9-15 J cm−2 range. The shot-to-shot laser energy fluctuation is less than 10 %. LIBS spectra are recorded in the 240-600 nm wavelength range using a step and glow mode at intervals of 30 nm. For the stratigraphic analysis (in-depth analysis), the LIBS spectra are recorded by applying several laser pulses in the same area of the sample. In general, the spectra are recorded at a 0.17 nm resolution with a gate delay and width of 200 ns and 3 μs, respectively. Cut-off filter at 300 is placed in front of the entrance window of the spectrograph to reduce the scattered laser light and to avoid second-order diffractions of elements emitting at lower wavelengths. Each LIBS spectrum is a result of a single signal acquisition as it provides good signal/noise ratios.

Dataset/Data package (images, spectra, other)
Report
spectra in *.csv

Micro-destructive (removal or permanent alteration of very small, inconspicuous portions)
Microinvasive (very minor, controlled, and reversible physical interaction)

Lotis TII LS-2147 (laser), Andor Shamrock (spectrograph), Andor Technologies (ICCD camera)

Custom

small spot
micro